Neural mechanisms of perceptual localization

描述（由申请人提供）：实际上，每一种视觉和视觉功能首先取决于视觉系统一致和准确地定位刺激的能力，这在混乱和动态的场景中尤其如此。然而，目前还不知道什么样的信息被整合来确定感知位置，这种整合是如何发生的，或者这个过程的神经机制和位点是什么。在典型的杂乱和动态场景中的感知定位需要视觉系统分配和更新对象位置;要做到这一点，它不仅依赖于感兴趣对象的视网膜位置，而且主要依赖于四个附加因素：视觉运动，参考系，偏心偏差，对比度适应。为了理解视觉系统如何分配和更新物体位置，我们必须将定位任务视为一个整体，而不是一个孤立的过程，它依赖于场景中的上下文信息。 我们提出的实验有两个目标：第一，心理测量感知位置作为视网膜位置，对比度适应，视觉运动，偏心偏差和参考系的函数，以产生一个新的多因子整合场模型;我们将在功能磁共振成像实验中使用这个模型来检验跨视觉皮层的神经定位组织是异质性的假设（每个视觉区域中的唯一位置代码）或同质（跨视觉区域相同）。我们的初步研究结果表明，在不同的视觉区域有独特的位置代码。该提案的第二个目标是测试这些独特的位置代码（地形组织的差异）是否具有感知后果。我们将使用心理物理学来测试这些预测的双重分离的感知位置，然后使用TMS来测试异质性视觉皮层地形组织感知位置的因果关系的贡献。我们的方法的一个新奇在于开发一个新的混合生成和判别模型的空间编码，可以应用于心理物理和功能磁共振成像数据串联，并进一步使我们能够预测功能磁共振成像结果的感知结果在特定情况下。功能磁共振成像结果和感知结果之间的因果关系，然后将与TMS进行测试。我们的实验将提供有关如何整合线索以确定视觉处理每个阶段的感知位置的新见解，这对于了解从弱视和黄斑变性到自闭症等一系列视觉和认知障碍中发生的基本定位缺陷至关重要。在我们了解典型大脑中的位置是如何分配的之前，我们缺乏必要的洞察力来开发诊断工具，预测标志物和治疗结果措施。

DESCRIPTION (provided by applicant): Virtually every visual and visuomotor function hinges first and foremost on the visual system's ability to consistently and accurately localize stimuli, and this is especially true in cluttered and dynamic scenes. However, it is unknown what sorts of information are integrated to determine perceived position, how such integration occurs, or what the neural mechanism(s) and loci of this process are. Perceptual localization in typically cluttered and dynamic scenes requires the visual system to both assign and update object positions; to do this it relies not just on the retinal location of the object of interest, but als principally on four additional factors: visual motion, frames of reference, eccentricity biases, an contrast adaptation. To understand how the visual system assigns and updates object positions, we must approach the task of localization not as an isolated process, but as an integrative one-one that depends on contextual information in the scene. Our proposed experiments have two goals; first, to psychophysically measure perceived position as a function of retinal position, contrast adaptation, visual motion, eccentricity bias, and frames of reference in order to generate a novel multifactorial integration field model; we will use this model in fMRI experiments to test the hypothesis that neurotopic organization across visual cortex is heterogeneous (unique position codes in each visual area) or homogeneous (identical across visual areas). Our pilot results suggest that there are unique position codes in different visual areas. The second goal of the proposal is to test whether these unique position codes (the differences in topographic organization) have perceptual consequences. We will use psychophysics to test these predicted double dissociations in perceived location and then use TMS to test the causal contribution of heterogeneous visual cortical topographic organization to perceived position. One novelty of our approach lies in developing a new mixed generative and discriminative model of spatial coding, that can be applied to psychophysical and fMRI data in tandem, and further allows us to make predictions from fMRI results about perceptual outcomes in specific situations. The causal relationship between fMRI results and perceptual outcomes will then be tested with TMS. Our experiments will provide novel insight on how cues are integrated to determine perceived position at each stage of visual processing, which is crucial to understanding the fundamental localization deficits that occur in a range of visual and cognitive impairments ranging from amblyopia and macular degeneration, to autism. Until we understand how position is assigned in the typical brain, we lack the necessary insight to develop diagnostic tools, predictive markers, and treatment outcome measures for these impairments.